| use std::cell::Cell; |
| use std::fmt; |
| use std::mem; |
| |
| use rustc_data_structures::stable_hasher::{HashStable, StableHasher}; |
| use rustc_hir::{self as hir, def_id::DefId, definitions::DefPathData}; |
| use rustc_index::vec::IndexVec; |
| use rustc_macros::HashStable; |
| use rustc_middle::mir; |
| use rustc_middle::mir::interpret::{InterpError, InvalidProgramInfo}; |
| use rustc_middle::ty::layout::{ |
| self, FnAbiError, FnAbiOfHelpers, FnAbiRequest, LayoutError, LayoutOf, LayoutOfHelpers, |
| TyAndLayout, |
| }; |
| use rustc_middle::ty::{ |
| self, query::TyCtxtAt, subst::SubstsRef, ParamEnv, Ty, TyCtxt, TypeFoldable, |
| }; |
| use rustc_mir_dataflow::storage::AlwaysLiveLocals; |
| use rustc_query_system::ich::StableHashingContext; |
| use rustc_session::Limit; |
| use rustc_span::{Pos, Span}; |
| use rustc_target::abi::{call::FnAbi, Align, HasDataLayout, Size, TargetDataLayout}; |
| |
| use super::{ |
| AllocId, GlobalId, Immediate, InterpErrorInfo, InterpResult, MPlaceTy, Machine, MemPlace, |
| MemPlaceMeta, Memory, MemoryKind, Operand, Place, PlaceTy, PointerArithmetic, Provenance, |
| Scalar, ScalarMaybeUninit, StackPopJump, |
| }; |
| use crate::transform::validate::equal_up_to_regions; |
| |
| pub struct InterpCx<'mir, 'tcx, M: Machine<'mir, 'tcx>> { |
| /// Stores the `Machine` instance. |
| /// |
| /// Note: the stack is provided by the machine. |
| pub machine: M, |
| |
| /// The results of the type checker, from rustc. |
| /// The span in this is the "root" of the evaluation, i.e., the const |
| /// we are evaluating (if this is CTFE). |
| pub tcx: TyCtxtAt<'tcx>, |
| |
| /// Bounds in scope for polymorphic evaluations. |
| pub(crate) param_env: ty::ParamEnv<'tcx>, |
| |
| /// The virtual memory system. |
| pub memory: Memory<'mir, 'tcx, M>, |
| |
| /// The recursion limit (cached from `tcx.recursion_limit(())`) |
| pub recursion_limit: Limit, |
| } |
| |
| // The Phantomdata exists to prevent this type from being `Send`. If it were sent across a thread |
| // boundary and dropped in the other thread, it would exit the span in the other thread. |
| struct SpanGuard(tracing::Span, std::marker::PhantomData<*const u8>); |
| |
| impl SpanGuard { |
| /// By default a `SpanGuard` does nothing. |
| fn new() -> Self { |
| Self(tracing::Span::none(), std::marker::PhantomData) |
| } |
| |
| /// If a span is entered, we exit the previous span (if any, normally none) and enter the |
| /// new span. This is mainly so we don't have to use `Option` for the `tracing_span` field of |
| /// `Frame` by creating a dummy span to being with and then entering it once the frame has |
| /// been pushed. |
| fn enter(&mut self, span: tracing::Span) { |
| // This executes the destructor on the previous instance of `SpanGuard`, ensuring that |
| // we never enter or exit more spans than vice versa. Unless you `mem::leak`, then we |
| // can't protect the tracing stack, but that'll just lead to weird logging, no actual |
| // problems. |
| *self = Self(span, std::marker::PhantomData); |
| self.0.with_subscriber(|(id, dispatch)| { |
| dispatch.enter(id); |
| }); |
| } |
| } |
| |
| impl Drop for SpanGuard { |
| fn drop(&mut self) { |
| self.0.with_subscriber(|(id, dispatch)| { |
| dispatch.exit(id); |
| }); |
| } |
| } |
| |
| /// A stack frame. |
| pub struct Frame<'mir, 'tcx, Tag: Provenance = AllocId, Extra = ()> { |
| //////////////////////////////////////////////////////////////////////////////// |
| // Function and callsite information |
| //////////////////////////////////////////////////////////////////////////////// |
| /// The MIR for the function called on this frame. |
| pub body: &'mir mir::Body<'tcx>, |
| |
| /// The def_id and substs of the current function. |
| pub instance: ty::Instance<'tcx>, |
| |
| /// Extra data for the machine. |
| pub extra: Extra, |
| |
| //////////////////////////////////////////////////////////////////////////////// |
| // Return place and locals |
| //////////////////////////////////////////////////////////////////////////////// |
| /// Work to perform when returning from this function. |
| pub return_to_block: StackPopCleanup, |
| |
| /// The location where the result of the current stack frame should be written to, |
| /// and its layout in the caller. |
| pub return_place: PlaceTy<'tcx, Tag>, |
| |
| /// The list of locals for this stack frame, stored in order as |
| /// `[return_ptr, arguments..., variables..., temporaries...]`. |
| /// The locals are stored as `Option<Value>`s. |
| /// `None` represents a local that is currently dead, while a live local |
| /// can either directly contain `Scalar` or refer to some part of an `Allocation`. |
| pub locals: IndexVec<mir::Local, LocalState<'tcx, Tag>>, |
| |
| /// The span of the `tracing` crate is stored here. |
| /// When the guard is dropped, the span is exited. This gives us |
| /// a full stack trace on all tracing statements. |
| tracing_span: SpanGuard, |
| |
| //////////////////////////////////////////////////////////////////////////////// |
| // Current position within the function |
| //////////////////////////////////////////////////////////////////////////////// |
| /// If this is `Err`, we are not currently executing any particular statement in |
| /// this frame (can happen e.g. during frame initialization, and during unwinding on |
| /// frames without cleanup code). |
| /// We basically abuse `Result` as `Either`. |
| pub(super) loc: Result<mir::Location, Span>, |
| } |
| |
| /// What we store about a frame in an interpreter backtrace. |
| #[derive(Debug)] |
| pub struct FrameInfo<'tcx> { |
| pub instance: ty::Instance<'tcx>, |
| pub span: Span, |
| pub lint_root: Option<hir::HirId>, |
| } |
| |
| /// Unwind information. |
| #[derive(Clone, Copy, Eq, PartialEq, Debug, HashStable)] |
| pub enum StackPopUnwind { |
| /// The cleanup block. |
| Cleanup(mir::BasicBlock), |
| /// No cleanup needs to be done. |
| Skip, |
| /// Unwinding is not allowed (UB). |
| NotAllowed, |
| } |
| |
| #[derive(Clone, Copy, Eq, PartialEq, Debug, HashStable)] // Miri debug-prints these |
| pub enum StackPopCleanup { |
| /// Jump to the next block in the caller, or cause UB if None (that's a function |
| /// that may never return). Also store layout of return place so |
| /// we can validate it at that layout. |
| /// `ret` stores the block we jump to on a normal return, while `unwind` |
| /// stores the block used for cleanup during unwinding. |
| Goto { ret: Option<mir::BasicBlock>, unwind: StackPopUnwind }, |
| /// The root frame of the stack: nowhere else to jump to. |
| /// `cleanup` says whether locals are deallocated. Static computation |
| /// wants them leaked to intern what they need (and just throw away |
| /// the entire `ecx` when it is done). |
| Root { cleanup: bool }, |
| } |
| |
| /// State of a local variable including a memoized layout |
| #[derive(Clone, Debug, PartialEq, Eq, HashStable)] |
| pub struct LocalState<'tcx, Tag: Provenance = AllocId> { |
| pub value: LocalValue<Tag>, |
| /// Don't modify if `Some`, this is only used to prevent computing the layout twice |
| #[stable_hasher(ignore)] |
| pub layout: Cell<Option<TyAndLayout<'tcx>>>, |
| } |
| |
| /// Current value of a local variable |
| #[derive(Copy, Clone, PartialEq, Eq, HashStable, Debug)] // Miri debug-prints these |
| pub enum LocalValue<Tag: Provenance = AllocId> { |
| /// This local is not currently alive, and cannot be used at all. |
| Dead, |
| /// This local is alive but not yet allocated. It cannot be read from or have its address taken, |
| /// and will be allocated on the first write. This is to support unsized locals, where we cannot |
| /// know their size in advance. |
| Unallocated, |
| /// A normal, live local. |
| /// Mostly for convenience, we re-use the `Operand` type here. |
| /// This is an optimization over just always having a pointer here; |
| /// we can thus avoid doing an allocation when the local just stores |
| /// immediate values *and* never has its address taken. |
| Live(Operand<Tag>), |
| } |
| |
| impl<'tcx, Tag: Provenance + 'static> LocalState<'tcx, Tag> { |
| /// Read the local's value or error if the local is not yet live or not live anymore. |
| /// |
| /// Note: This may only be invoked from the `Machine::access_local` hook and not from |
| /// anywhere else. You may be invalidating machine invariants if you do! |
| pub fn access(&self) -> InterpResult<'tcx, Operand<Tag>> { |
| match self.value { |
| LocalValue::Dead => throw_ub!(DeadLocal), |
| LocalValue::Unallocated => { |
| bug!("The type checker should prevent reading from a never-written local") |
| } |
| LocalValue::Live(val) => Ok(val), |
| } |
| } |
| |
| /// Overwrite the local. If the local can be overwritten in place, return a reference |
| /// to do so; otherwise return the `MemPlace` to consult instead. |
| /// |
| /// Note: This may only be invoked from the `Machine::access_local_mut` hook and not from |
| /// anywhere else. You may be invalidating machine invariants if you do! |
| pub fn access_mut( |
| &mut self, |
| ) -> InterpResult<'tcx, Result<&mut LocalValue<Tag>, MemPlace<Tag>>> { |
| match self.value { |
| LocalValue::Dead => throw_ub!(DeadLocal), |
| LocalValue::Live(Operand::Indirect(mplace)) => Ok(Err(mplace)), |
| ref mut local @ (LocalValue::Live(Operand::Immediate(_)) | LocalValue::Unallocated) => { |
| Ok(Ok(local)) |
| } |
| } |
| } |
| } |
| |
| impl<'mir, 'tcx, Tag: Provenance> Frame<'mir, 'tcx, Tag> { |
| pub fn with_extra<Extra>(self, extra: Extra) -> Frame<'mir, 'tcx, Tag, Extra> { |
| Frame { |
| body: self.body, |
| instance: self.instance, |
| return_to_block: self.return_to_block, |
| return_place: self.return_place, |
| locals: self.locals, |
| loc: self.loc, |
| extra, |
| tracing_span: self.tracing_span, |
| } |
| } |
| } |
| |
| impl<'mir, 'tcx, Tag: Provenance, Extra> Frame<'mir, 'tcx, Tag, Extra> { |
| /// Get the current location within the Frame. |
| /// |
| /// If this is `Err`, we are not currently executing any particular statement in |
| /// this frame (can happen e.g. during frame initialization, and during unwinding on |
| /// frames without cleanup code). |
| /// We basically abuse `Result` as `Either`. |
| /// |
| /// Used by priroda. |
| pub fn current_loc(&self) -> Result<mir::Location, Span> { |
| self.loc |
| } |
| |
| /// Return the `SourceInfo` of the current instruction. |
| pub fn current_source_info(&self) -> Option<&mir::SourceInfo> { |
| self.loc.ok().map(|loc| self.body.source_info(loc)) |
| } |
| |
| pub fn current_span(&self) -> Span { |
| match self.loc { |
| Ok(loc) => self.body.source_info(loc).span, |
| Err(span) => span, |
| } |
| } |
| } |
| |
| impl<'tcx> fmt::Display for FrameInfo<'tcx> { |
| fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { |
| ty::tls::with(|tcx| { |
| if tcx.def_key(self.instance.def_id()).disambiguated_data.data |
| == DefPathData::ClosureExpr |
| { |
| write!(f, "inside closure")?; |
| } else { |
| write!(f, "inside `{}`", self.instance)?; |
| } |
| if !self.span.is_dummy() { |
| let sm = tcx.sess.source_map(); |
| let lo = sm.lookup_char_pos(self.span.lo()); |
| write!( |
| f, |
| " at {}:{}:{}", |
| sm.filename_for_diagnostics(&lo.file.name), |
| lo.line, |
| lo.col.to_usize() + 1 |
| )?; |
| } |
| Ok(()) |
| }) |
| } |
| } |
| |
| impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> HasDataLayout for InterpCx<'mir, 'tcx, M> { |
| #[inline] |
| fn data_layout(&self) -> &TargetDataLayout { |
| &self.tcx.data_layout |
| } |
| } |
| |
| impl<'mir, 'tcx, M> layout::HasTyCtxt<'tcx> for InterpCx<'mir, 'tcx, M> |
| where |
| M: Machine<'mir, 'tcx>, |
| { |
| #[inline] |
| fn tcx(&self) -> TyCtxt<'tcx> { |
| *self.tcx |
| } |
| } |
| |
| impl<'mir, 'tcx, M> layout::HasParamEnv<'tcx> for InterpCx<'mir, 'tcx, M> |
| where |
| M: Machine<'mir, 'tcx>, |
| { |
| fn param_env(&self) -> ty::ParamEnv<'tcx> { |
| self.param_env |
| } |
| } |
| |
| impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> LayoutOfHelpers<'tcx> for InterpCx<'mir, 'tcx, M> { |
| type LayoutOfResult = InterpResult<'tcx, TyAndLayout<'tcx>>; |
| |
| #[inline] |
| fn layout_tcx_at_span(&self) -> Span { |
| self.tcx.span |
| } |
| |
| #[inline] |
| fn handle_layout_err( |
| &self, |
| err: LayoutError<'tcx>, |
| _: Span, |
| _: Ty<'tcx>, |
| ) -> InterpErrorInfo<'tcx> { |
| err_inval!(Layout(err)).into() |
| } |
| } |
| |
| impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> FnAbiOfHelpers<'tcx> for InterpCx<'mir, 'tcx, M> { |
| type FnAbiOfResult = InterpResult<'tcx, &'tcx FnAbi<'tcx, Ty<'tcx>>>; |
| |
| fn handle_fn_abi_err( |
| &self, |
| err: FnAbiError<'tcx>, |
| _span: Span, |
| _fn_abi_request: FnAbiRequest<'tcx>, |
| ) -> InterpErrorInfo<'tcx> { |
| match err { |
| FnAbiError::Layout(err) => err_inval!(Layout(err)).into(), |
| FnAbiError::AdjustForForeignAbi(err) => { |
| err_inval!(FnAbiAdjustForForeignAbi(err)).into() |
| } |
| } |
| } |
| } |
| |
| /// Test if it is valid for a MIR assignment to assign `src`-typed place to `dest`-typed value. |
| /// This test should be symmetric, as it is primarily about layout compatibility. |
| pub(super) fn mir_assign_valid_types<'tcx>( |
| tcx: TyCtxt<'tcx>, |
| param_env: ParamEnv<'tcx>, |
| src: TyAndLayout<'tcx>, |
| dest: TyAndLayout<'tcx>, |
| ) -> bool { |
| // Type-changing assignments can happen when subtyping is used. While |
| // all normal lifetimes are erased, higher-ranked types with their |
| // late-bound lifetimes are still around and can lead to type |
| // differences. So we compare ignoring lifetimes. |
| if equal_up_to_regions(tcx, param_env, src.ty, dest.ty) { |
| // Make sure the layout is equal, too -- just to be safe. Miri really |
| // needs layout equality. For performance reason we skip this check when |
| // the types are equal. Equal types *can* have different layouts when |
| // enum downcast is involved (as enum variants carry the type of the |
| // enum), but those should never occur in assignments. |
| if cfg!(debug_assertions) || src.ty != dest.ty { |
| assert_eq!(src.layout, dest.layout); |
| } |
| true |
| } else { |
| false |
| } |
| } |
| |
| /// Use the already known layout if given (but sanity check in debug mode), |
| /// or compute the layout. |
| #[cfg_attr(not(debug_assertions), inline(always))] |
| pub(super) fn from_known_layout<'tcx>( |
| tcx: TyCtxtAt<'tcx>, |
| param_env: ParamEnv<'tcx>, |
| known_layout: Option<TyAndLayout<'tcx>>, |
| compute: impl FnOnce() -> InterpResult<'tcx, TyAndLayout<'tcx>>, |
| ) -> InterpResult<'tcx, TyAndLayout<'tcx>> { |
| match known_layout { |
| None => compute(), |
| Some(known_layout) => { |
| if cfg!(debug_assertions) { |
| let check_layout = compute()?; |
| if !mir_assign_valid_types(tcx.tcx, param_env, check_layout, known_layout) { |
| span_bug!( |
| tcx.span, |
| "expected type differs from actual type.\nexpected: {:?}\nactual: {:?}", |
| known_layout.ty, |
| check_layout.ty, |
| ); |
| } |
| } |
| Ok(known_layout) |
| } |
| } |
| } |
| |
| impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> { |
| pub fn new( |
| tcx: TyCtxt<'tcx>, |
| root_span: Span, |
| param_env: ty::ParamEnv<'tcx>, |
| machine: M, |
| ) -> Self { |
| InterpCx { |
| machine, |
| tcx: tcx.at(root_span), |
| param_env, |
| memory: Memory::new(), |
| recursion_limit: tcx.recursion_limit(), |
| } |
| } |
| |
| #[inline(always)] |
| pub fn cur_span(&self) -> Span { |
| self.stack() |
| .iter() |
| .rev() |
| .find(|frame| !frame.instance.def.requires_caller_location(*self.tcx)) |
| .map_or(self.tcx.span, |f| f.current_span()) |
| } |
| |
| #[inline(always)] |
| pub(crate) fn stack(&self) -> &[Frame<'mir, 'tcx, M::PointerTag, M::FrameExtra>] { |
| M::stack(self) |
| } |
| |
| #[inline(always)] |
| pub(crate) fn stack_mut( |
| &mut self, |
| ) -> &mut Vec<Frame<'mir, 'tcx, M::PointerTag, M::FrameExtra>> { |
| M::stack_mut(self) |
| } |
| |
| #[inline(always)] |
| pub fn frame_idx(&self) -> usize { |
| let stack = self.stack(); |
| assert!(!stack.is_empty()); |
| stack.len() - 1 |
| } |
| |
| #[inline(always)] |
| pub fn frame(&self) -> &Frame<'mir, 'tcx, M::PointerTag, M::FrameExtra> { |
| self.stack().last().expect("no call frames exist") |
| } |
| |
| #[inline(always)] |
| pub fn frame_mut(&mut self) -> &mut Frame<'mir, 'tcx, M::PointerTag, M::FrameExtra> { |
| self.stack_mut().last_mut().expect("no call frames exist") |
| } |
| |
| #[inline(always)] |
| pub(super) fn body(&self) -> &'mir mir::Body<'tcx> { |
| self.frame().body |
| } |
| |
| #[inline(always)] |
| pub fn sign_extend(&self, value: u128, ty: TyAndLayout<'_>) -> u128 { |
| assert!(ty.abi.is_signed()); |
| ty.size.sign_extend(value) |
| } |
| |
| #[inline(always)] |
| pub fn truncate(&self, value: u128, ty: TyAndLayout<'_>) -> u128 { |
| ty.size.truncate(value) |
| } |
| |
| #[inline] |
| pub fn type_is_freeze(&self, ty: Ty<'tcx>) -> bool { |
| ty.is_freeze(self.tcx, self.param_env) |
| } |
| |
| pub fn load_mir( |
| &self, |
| instance: ty::InstanceDef<'tcx>, |
| promoted: Option<mir::Promoted>, |
| ) -> InterpResult<'tcx, &'tcx mir::Body<'tcx>> { |
| let def = instance.with_opt_param(); |
| trace!("load mir(instance={:?}, promoted={:?})", instance, promoted); |
| let body = if let Some(promoted) = promoted { |
| &self.tcx.promoted_mir_opt_const_arg(def)[promoted] |
| } else { |
| M::load_mir(self, instance)? |
| }; |
| // do not continue if typeck errors occurred (can only occur in local crate) |
| if let Some(err) = body.tainted_by_errors { |
| throw_inval!(AlreadyReported(err)); |
| } |
| Ok(body) |
| } |
| |
| /// Call this on things you got out of the MIR (so it is as generic as the current |
| /// stack frame), to bring it into the proper environment for this interpreter. |
| pub(super) fn subst_from_current_frame_and_normalize_erasing_regions<T: TypeFoldable<'tcx>>( |
| &self, |
| value: T, |
| ) -> Result<T, InterpError<'tcx>> { |
| self.subst_from_frame_and_normalize_erasing_regions(self.frame(), value) |
| } |
| |
| /// Call this on things you got out of the MIR (so it is as generic as the provided |
| /// stack frame), to bring it into the proper environment for this interpreter. |
| pub(super) fn subst_from_frame_and_normalize_erasing_regions<T: TypeFoldable<'tcx>>( |
| &self, |
| frame: &Frame<'mir, 'tcx, M::PointerTag, M::FrameExtra>, |
| value: T, |
| ) -> Result<T, InterpError<'tcx>> { |
| frame |
| .instance |
| .try_subst_mir_and_normalize_erasing_regions(*self.tcx, self.param_env, value) |
| .map_err(|e| { |
| self.tcx.sess.delay_span_bug( |
| self.cur_span(), |
| format!("failed to normalize {}", e.get_type_for_failure()).as_str(), |
| ); |
| |
| InterpError::InvalidProgram(InvalidProgramInfo::TooGeneric) |
| }) |
| } |
| |
| /// The `substs` are assumed to already be in our interpreter "universe" (param_env). |
| pub(super) fn resolve( |
| &self, |
| def: ty::WithOptConstParam<DefId>, |
| substs: SubstsRef<'tcx>, |
| ) -> InterpResult<'tcx, ty::Instance<'tcx>> { |
| trace!("resolve: {:?}, {:#?}", def, substs); |
| trace!("param_env: {:#?}", self.param_env); |
| trace!("substs: {:#?}", substs); |
| match ty::Instance::resolve_opt_const_arg(*self.tcx, self.param_env, def, substs) { |
| Ok(Some(instance)) => Ok(instance), |
| Ok(None) => throw_inval!(TooGeneric), |
| |
| // FIXME(eddyb) this could be a bit more specific than `AlreadyReported`. |
| Err(error_reported) => throw_inval!(AlreadyReported(error_reported)), |
| } |
| } |
| |
| #[inline(always)] |
| pub fn layout_of_local( |
| &self, |
| frame: &Frame<'mir, 'tcx, M::PointerTag, M::FrameExtra>, |
| local: mir::Local, |
| layout: Option<TyAndLayout<'tcx>>, |
| ) -> InterpResult<'tcx, TyAndLayout<'tcx>> { |
| // `const_prop` runs into this with an invalid (empty) frame, so we |
| // have to support that case (mostly by skipping all caching). |
| match frame.locals.get(local).and_then(|state| state.layout.get()) { |
| None => { |
| let layout = from_known_layout(self.tcx, self.param_env, layout, || { |
| let local_ty = frame.body.local_decls[local].ty; |
| let local_ty = |
| self.subst_from_frame_and_normalize_erasing_regions(frame, local_ty)?; |
| self.layout_of(local_ty) |
| })?; |
| if let Some(state) = frame.locals.get(local) { |
| // Layouts of locals are requested a lot, so we cache them. |
| state.layout.set(Some(layout)); |
| } |
| Ok(layout) |
| } |
| Some(layout) => Ok(layout), |
| } |
| } |
| |
| /// Returns the actual dynamic size and alignment of the place at the given type. |
| /// Only the "meta" (metadata) part of the place matters. |
| /// This can fail to provide an answer for extern types. |
| pub(super) fn size_and_align_of( |
| &self, |
| metadata: &MemPlaceMeta<M::PointerTag>, |
| layout: &TyAndLayout<'tcx>, |
| ) -> InterpResult<'tcx, Option<(Size, Align)>> { |
| if !layout.is_unsized() { |
| return Ok(Some((layout.size, layout.align.abi))); |
| } |
| match layout.ty.kind() { |
| ty::Adt(..) | ty::Tuple(..) => { |
| // First get the size of all statically known fields. |
| // Don't use type_of::sizing_type_of because that expects t to be sized, |
| // and it also rounds up to alignment, which we want to avoid, |
| // as the unsized field's alignment could be smaller. |
| assert!(!layout.ty.is_simd()); |
| assert!(layout.fields.count() > 0); |
| trace!("DST layout: {:?}", layout); |
| |
| let sized_size = layout.fields.offset(layout.fields.count() - 1); |
| let sized_align = layout.align.abi; |
| trace!( |
| "DST {} statically sized prefix size: {:?} align: {:?}", |
| layout.ty, |
| sized_size, |
| sized_align |
| ); |
| |
| // Recurse to get the size of the dynamically sized field (must be |
| // the last field). Can't have foreign types here, how would we |
| // adjust alignment and size for them? |
| let field = layout.field(self, layout.fields.count() - 1); |
| let Some((unsized_size, unsized_align)) = self.size_and_align_of(metadata, &field)? else { |
| // A field with an extern type. We don't know the actual dynamic size |
| // or the alignment. |
| return Ok(None); |
| }; |
| |
| // FIXME (#26403, #27023): We should be adding padding |
| // to `sized_size` (to accommodate the `unsized_align` |
| // required of the unsized field that follows) before |
| // summing it with `sized_size`. (Note that since #26403 |
| // is unfixed, we do not yet add the necessary padding |
| // here. But this is where the add would go.) |
| |
| // Return the sum of sizes and max of aligns. |
| let size = sized_size + unsized_size; // `Size` addition |
| |
| // Choose max of two known alignments (combined value must |
| // be aligned according to more restrictive of the two). |
| let align = sized_align.max(unsized_align); |
| |
| // Issue #27023: must add any necessary padding to `size` |
| // (to make it a multiple of `align`) before returning it. |
| let size = size.align_to(align); |
| |
| // Check if this brought us over the size limit. |
| if size > self.max_size_of_val() { |
| throw_ub!(InvalidMeta("total size is bigger than largest supported object")); |
| } |
| Ok(Some((size, align))) |
| } |
| ty::Dynamic(..) => { |
| let vtable = self.scalar_to_ptr(metadata.unwrap_meta())?; |
| // Read size and align from vtable (already checks size). |
| Ok(Some(self.read_size_and_align_from_vtable(vtable)?)) |
| } |
| |
| ty::Slice(_) | ty::Str => { |
| let len = metadata.unwrap_meta().to_machine_usize(self)?; |
| let elem = layout.field(self, 0); |
| |
| // Make sure the slice is not too big. |
| let size = elem.size.bytes().saturating_mul(len); // we rely on `max_size_of_val` being smaller than `u64::MAX`. |
| let size = Size::from_bytes(size); |
| if size > self.max_size_of_val() { |
| throw_ub!(InvalidMeta("slice is bigger than largest supported object")); |
| } |
| Ok(Some((size, elem.align.abi))) |
| } |
| |
| ty::Foreign(_) => Ok(None), |
| |
| _ => span_bug!(self.cur_span(), "size_and_align_of::<{:?}> not supported", layout.ty), |
| } |
| } |
| #[inline] |
| pub fn size_and_align_of_mplace( |
| &self, |
| mplace: &MPlaceTy<'tcx, M::PointerTag>, |
| ) -> InterpResult<'tcx, Option<(Size, Align)>> { |
| self.size_and_align_of(&mplace.meta, &mplace.layout) |
| } |
| |
| #[instrument(skip(self, body, return_place, return_to_block), level = "debug")] |
| pub fn push_stack_frame( |
| &mut self, |
| instance: ty::Instance<'tcx>, |
| body: &'mir mir::Body<'tcx>, |
| return_place: &PlaceTy<'tcx, M::PointerTag>, |
| return_to_block: StackPopCleanup, |
| ) -> InterpResult<'tcx> { |
| trace!("body: {:#?}", body); |
| // first push a stack frame so we have access to the local substs |
| let pre_frame = Frame { |
| body, |
| loc: Err(body.span), // Span used for errors caused during preamble. |
| return_to_block, |
| return_place: *return_place, |
| // empty local array, we fill it in below, after we are inside the stack frame and |
| // all methods actually know about the frame |
| locals: IndexVec::new(), |
| instance, |
| tracing_span: SpanGuard::new(), |
| extra: (), |
| }; |
| let frame = M::init_frame_extra(self, pre_frame)?; |
| self.stack_mut().push(frame); |
| |
| // Make sure all the constants required by this frame evaluate successfully (post-monomorphization check). |
| for const_ in &body.required_consts { |
| let span = const_.span; |
| let const_ = |
| self.subst_from_current_frame_and_normalize_erasing_regions(const_.literal)?; |
| self.mir_const_to_op(&const_, None).map_err(|err| { |
| // If there was an error, set the span of the current frame to this constant. |
| // Avoiding doing this when evaluation succeeds. |
| self.frame_mut().loc = Err(span); |
| err |
| })?; |
| } |
| |
| // Locals are initially unallocated. |
| let dummy = LocalState { value: LocalValue::Unallocated, layout: Cell::new(None) }; |
| let mut locals = IndexVec::from_elem(dummy, &body.local_decls); |
| |
| // Now mark those locals as dead that we do not want to initialize |
| // Mark locals that use `Storage*` annotations as dead on function entry. |
| let always_live = AlwaysLiveLocals::new(self.body()); |
| for local in locals.indices() { |
| if !always_live.contains(local) { |
| locals[local].value = LocalValue::Dead; |
| } |
| } |
| // done |
| self.frame_mut().locals = locals; |
| M::after_stack_push(self)?; |
| self.frame_mut().loc = Ok(mir::Location::START); |
| |
| let span = info_span!("frame", "{}", instance); |
| self.frame_mut().tracing_span.enter(span); |
| |
| Ok(()) |
| } |
| |
| /// Jump to the given block. |
| #[inline] |
| pub fn go_to_block(&mut self, target: mir::BasicBlock) { |
| self.frame_mut().loc = Ok(mir::Location { block: target, statement_index: 0 }); |
| } |
| |
| /// *Return* to the given `target` basic block. |
| /// Do *not* use for unwinding! Use `unwind_to_block` instead. |
| /// |
| /// If `target` is `None`, that indicates the function cannot return, so we raise UB. |
| pub fn return_to_block(&mut self, target: Option<mir::BasicBlock>) -> InterpResult<'tcx> { |
| if let Some(target) = target { |
| self.go_to_block(target); |
| Ok(()) |
| } else { |
| throw_ub!(Unreachable) |
| } |
| } |
| |
| /// *Unwind* to the given `target` basic block. |
| /// Do *not* use for returning! Use `return_to_block` instead. |
| /// |
| /// If `target` is `StackPopUnwind::Skip`, that indicates the function does not need cleanup |
| /// during unwinding, and we will just keep propagating that upwards. |
| /// |
| /// If `target` is `StackPopUnwind::NotAllowed`, that indicates the function does not allow |
| /// unwinding, and doing so is UB. |
| pub fn unwind_to_block(&mut self, target: StackPopUnwind) -> InterpResult<'tcx> { |
| self.frame_mut().loc = match target { |
| StackPopUnwind::Cleanup(block) => Ok(mir::Location { block, statement_index: 0 }), |
| StackPopUnwind::Skip => Err(self.frame_mut().body.span), |
| StackPopUnwind::NotAllowed => { |
| throw_ub_format!("unwinding past a stack frame that does not allow unwinding") |
| } |
| }; |
| Ok(()) |
| } |
| |
| /// Pops the current frame from the stack, deallocating the |
| /// memory for allocated locals. |
| /// |
| /// If `unwinding` is `false`, then we are performing a normal return |
| /// from a function. In this case, we jump back into the frame of the caller, |
| /// and continue execution as normal. |
| /// |
| /// If `unwinding` is `true`, then we are in the middle of a panic, |
| /// and need to unwind this frame. In this case, we jump to the |
| /// `cleanup` block for the function, which is responsible for running |
| /// `Drop` impls for any locals that have been initialized at this point. |
| /// The cleanup block ends with a special `Resume` terminator, which will |
| /// cause us to continue unwinding. |
| #[instrument(skip(self), level = "debug")] |
| pub(super) fn pop_stack_frame(&mut self, unwinding: bool) -> InterpResult<'tcx> { |
| info!( |
| "popping stack frame ({})", |
| if unwinding { "during unwinding" } else { "returning from function" } |
| ); |
| |
| // Sanity check `unwinding`. |
| assert_eq!( |
| unwinding, |
| match self.frame().loc { |
| Ok(loc) => self.body().basic_blocks()[loc.block].is_cleanup, |
| Err(_) => true, |
| } |
| ); |
| |
| if unwinding && self.frame_idx() == 0 { |
| throw_ub_format!("unwinding past the topmost frame of the stack"); |
| } |
| |
| let frame = |
| self.stack_mut().pop().expect("tried to pop a stack frame, but there were none"); |
| |
| if !unwinding { |
| let op = self.access_local(&frame, mir::RETURN_PLACE, None)?; |
| self.copy_op_transmute(&op, &frame.return_place)?; |
| trace!("{:?}", self.dump_place(*frame.return_place)); |
| } |
| |
| let return_to_block = frame.return_to_block; |
| |
| // Now where do we jump next? |
| |
| // Usually we want to clean up (deallocate locals), but in a few rare cases we don't. |
| // In that case, we return early. We also avoid validation in that case, |
| // because this is CTFE and the final value will be thoroughly validated anyway. |
| let cleanup = match return_to_block { |
| StackPopCleanup::Goto { .. } => true, |
| StackPopCleanup::Root { cleanup, .. } => cleanup, |
| }; |
| |
| if !cleanup { |
| assert!(self.stack().is_empty(), "only the topmost frame should ever be leaked"); |
| assert!(!unwinding, "tried to skip cleanup during unwinding"); |
| // Leak the locals, skip validation, skip machine hook. |
| return Ok(()); |
| } |
| |
| trace!("locals: {:#?}", frame.locals); |
| |
| // Cleanup: deallocate all locals that are backed by an allocation. |
| for local in &frame.locals { |
| self.deallocate_local(local.value)?; |
| } |
| |
| if M::after_stack_pop(self, frame, unwinding)? == StackPopJump::NoJump { |
| // The hook already did everything. |
| // We want to skip the `info!` below, hence early return. |
| return Ok(()); |
| } |
| // Normal return, figure out where to jump. |
| if unwinding { |
| // Follow the unwind edge. |
| let unwind = match return_to_block { |
| StackPopCleanup::Goto { unwind, .. } => unwind, |
| StackPopCleanup::Root { .. } => { |
| panic!("encountered StackPopCleanup::Root when unwinding!") |
| } |
| }; |
| self.unwind_to_block(unwind) |
| } else { |
| // Follow the normal return edge. |
| match return_to_block { |
| StackPopCleanup::Goto { ret, .. } => self.return_to_block(ret), |
| StackPopCleanup::Root { .. } => { |
| assert!( |
| self.stack().is_empty(), |
| "only the topmost frame can have StackPopCleanup::Root" |
| ); |
| Ok(()) |
| } |
| } |
| } |
| } |
| |
| /// Mark a storage as live, killing the previous content. |
| pub fn storage_live(&mut self, local: mir::Local) -> InterpResult<'tcx> { |
| assert!(local != mir::RETURN_PLACE, "Cannot make return place live"); |
| trace!("{:?} is now live", local); |
| |
| let local_val = LocalValue::Unallocated; |
| // StorageLive expects the local to be dead, and marks it live. |
| let old = mem::replace(&mut self.frame_mut().locals[local].value, local_val); |
| if !matches!(old, LocalValue::Dead) { |
| throw_ub_format!("StorageLive on a local that was already live"); |
| } |
| Ok(()) |
| } |
| |
| pub fn storage_dead(&mut self, local: mir::Local) -> InterpResult<'tcx> { |
| assert!(local != mir::RETURN_PLACE, "Cannot make return place dead"); |
| trace!("{:?} is now dead", local); |
| |
| // It is entirely okay for this local to be already dead (at least that's how we currently generate MIR) |
| let old = mem::replace(&mut self.frame_mut().locals[local].value, LocalValue::Dead); |
| self.deallocate_local(old)?; |
| Ok(()) |
| } |
| |
| #[instrument(skip(self), level = "debug")] |
| fn deallocate_local(&mut self, local: LocalValue<M::PointerTag>) -> InterpResult<'tcx> { |
| if let LocalValue::Live(Operand::Indirect(MemPlace { ptr, .. })) = local { |
| // All locals have a backing allocation, even if the allocation is empty |
| // due to the local having ZST type. Hence we can `unwrap`. |
| trace!( |
| "deallocating local {:?}: {:?}", |
| local, |
| // Locals always have a `alloc_id` (they are never the result of a int2ptr). |
| self.dump_alloc(ptr.provenance.unwrap().get_alloc_id().unwrap()) |
| ); |
| self.deallocate_ptr(ptr, None, MemoryKind::Stack)?; |
| }; |
| Ok(()) |
| } |
| |
| pub fn eval_to_allocation( |
| &self, |
| gid: GlobalId<'tcx>, |
| ) -> InterpResult<'tcx, MPlaceTy<'tcx, M::PointerTag>> { |
| // For statics we pick `ParamEnv::reveal_all`, because statics don't have generics |
| // and thus don't care about the parameter environment. While we could just use |
| // `self.param_env`, that would mean we invoke the query to evaluate the static |
| // with different parameter environments, thus causing the static to be evaluated |
| // multiple times. |
| let param_env = if self.tcx.is_static(gid.instance.def_id()) { |
| ty::ParamEnv::reveal_all() |
| } else { |
| self.param_env |
| }; |
| let param_env = param_env.with_const(); |
| let val = self.tcx.eval_to_allocation_raw(param_env.and(gid))?; |
| self.raw_const_to_mplace(val) |
| } |
| |
| #[must_use] |
| pub fn dump_place(&self, place: Place<M::PointerTag>) -> PlacePrinter<'_, 'mir, 'tcx, M> { |
| PlacePrinter { ecx: self, place } |
| } |
| |
| #[must_use] |
| pub fn generate_stacktrace(&self) -> Vec<FrameInfo<'tcx>> { |
| let mut frames = Vec::new(); |
| for frame in self |
| .stack() |
| .iter() |
| .rev() |
| .skip_while(|frame| frame.instance.def.requires_caller_location(*self.tcx)) |
| { |
| let lint_root = frame.current_source_info().and_then(|source_info| { |
| match &frame.body.source_scopes[source_info.scope].local_data { |
| mir::ClearCrossCrate::Set(data) => Some(data.lint_root), |
| mir::ClearCrossCrate::Clear => None, |
| } |
| }); |
| let span = frame.current_span(); |
| |
| frames.push(FrameInfo { span, instance: frame.instance, lint_root }); |
| } |
| trace!("generate stacktrace: {:#?}", frames); |
| frames |
| } |
| } |
| |
| #[doc(hidden)] |
| /// Helper struct for the `dump_place` function. |
| pub struct PlacePrinter<'a, 'mir, 'tcx, M: Machine<'mir, 'tcx>> { |
| ecx: &'a InterpCx<'mir, 'tcx, M>, |
| place: Place<M::PointerTag>, |
| } |
| |
| impl<'a, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> std::fmt::Debug |
| for PlacePrinter<'a, 'mir, 'tcx, M> |
| { |
| fn fmt(&self, fmt: &mut std::fmt::Formatter<'_>) -> std::fmt::Result { |
| match self.place { |
| Place::Local { frame, local } => { |
| let mut allocs = Vec::new(); |
| write!(fmt, "{:?}", local)?; |
| if frame != self.ecx.frame_idx() { |
| write!(fmt, " ({} frames up)", self.ecx.frame_idx() - frame)?; |
| } |
| write!(fmt, ":")?; |
| |
| match self.ecx.stack()[frame].locals[local].value { |
| LocalValue::Dead => write!(fmt, " is dead")?, |
| LocalValue::Unallocated => write!(fmt, " is unallocated")?, |
| LocalValue::Live(Operand::Indirect(mplace)) => { |
| write!( |
| fmt, |
| " by align({}){} ref {:?}:", |
| mplace.align.bytes(), |
| match mplace.meta { |
| MemPlaceMeta::Meta(meta) => format!(" meta({:?})", meta), |
| MemPlaceMeta::Poison | MemPlaceMeta::None => String::new(), |
| }, |
| mplace.ptr, |
| )?; |
| allocs.extend(mplace.ptr.provenance.map(Provenance::get_alloc_id)); |
| } |
| LocalValue::Live(Operand::Immediate(Immediate::Scalar(val))) => { |
| write!(fmt, " {:?}", val)?; |
| if let ScalarMaybeUninit::Scalar(Scalar::Ptr(ptr, _size)) = val { |
| allocs.push(ptr.provenance.get_alloc_id()); |
| } |
| } |
| LocalValue::Live(Operand::Immediate(Immediate::ScalarPair(val1, val2))) => { |
| write!(fmt, " ({:?}, {:?})", val1, val2)?; |
| if let ScalarMaybeUninit::Scalar(Scalar::Ptr(ptr, _size)) = val1 { |
| allocs.push(ptr.provenance.get_alloc_id()); |
| } |
| if let ScalarMaybeUninit::Scalar(Scalar::Ptr(ptr, _size)) = val2 { |
| allocs.push(ptr.provenance.get_alloc_id()); |
| } |
| } |
| } |
| |
| write!(fmt, ": {:?}", self.ecx.dump_allocs(allocs.into_iter().flatten().collect())) |
| } |
| Place::Ptr(mplace) => match mplace.ptr.provenance.and_then(Provenance::get_alloc_id) { |
| Some(alloc_id) => write!( |
| fmt, |
| "by align({}) ref {:?}: {:?}", |
| mplace.align.bytes(), |
| mplace.ptr, |
| self.ecx.dump_alloc(alloc_id) |
| ), |
| ptr => write!(fmt, " integral by ref: {:?}", ptr), |
| }, |
| } |
| } |
| } |
| |
| impl<'ctx, 'mir, 'tcx, Tag: Provenance, Extra> HashStable<StableHashingContext<'ctx>> |
| for Frame<'mir, 'tcx, Tag, Extra> |
| where |
| Extra: HashStable<StableHashingContext<'ctx>>, |
| Tag: HashStable<StableHashingContext<'ctx>>, |
| { |
| fn hash_stable(&self, hcx: &mut StableHashingContext<'ctx>, hasher: &mut StableHasher) { |
| // Exhaustive match on fields to make sure we forget no field. |
| let Frame { |
| body, |
| instance, |
| return_to_block, |
| return_place, |
| locals, |
| loc, |
| extra, |
| tracing_span: _, |
| } = self; |
| body.hash_stable(hcx, hasher); |
| instance.hash_stable(hcx, hasher); |
| return_to_block.hash_stable(hcx, hasher); |
| return_place.hash_stable(hcx, hasher); |
| locals.hash_stable(hcx, hasher); |
| loc.hash_stable(hcx, hasher); |
| extra.hash_stable(hcx, hasher); |
| } |
| } |
